Can you use a rogers wireless iPhone on ATT's network?

Sure can! Just call up AT&T and tell them you are going out of the country for a month or so. If you are a customer in good standing they will give you the unlock code for your phone, which allows you to use other provider SIM cards for it. NOTE: This works in Canada because the use the same frequencies for GSM as the US. If you are going to Europe, you need to have a Quad-Band "World Phone" to use their frequencies.